@unpublished{tram:advml23, author = "Tsai, Yun-Yun and Chao, Ju-Chin and Wen, Albert and Yang, Zhaoyuan and Mao, Chengzhi and Shah, Tapan and Yang, Junfeng", abstract = "Training-time defenses, known as adversarial training, incur high training costs and do not generalize to unseen attacks. Test-time defenses solve these issues but most existing test-time defenses require adapting the model weights, therefore they do not work on frozen models and complicate model memory management. The only test-time defense that does not adapt model weights aims to adapt the input with self-supervision tasks. However, we empirically found these self-supervision tasks are not sensitive enough to detect adversarial attacks accurately. In this paper, we propose DRAM, a novel defense method to detect and repair adversarial samples at test time via Masked autoencoder (MAE). We demonstrate how to use MAE losses to build a Kolmogorov-Smirnov test to detect adversarial samples. Moreover, we use the MAE losses to calculate input reversal vectors that repair adversarial samples resulting from previously unseen attacks. Results on large-scale ImageNet dataset show that, compared to all detection baselines evaluated, DRAM achieves the best detection rate (82\% on average) on all eight adversarial attacks evaluated. For attack repair, DRAM improves the robust accuracy by 6\%∼41\% for standard ResNet50 and 3\%∼8\% for robust ResNet50 compared with the baselines that use contrastive learning and rotation prediction.", title = "Test-time Detection and Repair of Adversarial Samples via Masked Autoencoder", booktitle = "3rd Workshop of Adversarial Machine Learning on Computer Vision: Art of Robustness (AdvML), held with CVPR", note = "3rd Workshop of Adversarial Machine Learning on Computer Vision: Art of Robustness (AdvML), held with CVPR; non-archival workshop paper", month = "June", eprint = "2303.12848", archivePrefix = "arXiv", primaryClass = "cs.CV", url = "https://arxiv.org/abs/2303.12848", pdfurl = "https://arxiv.org/pdf/2303.12848", year = "2023" }